Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6138, USA.
Phys Rev Lett. 2013 Jun 28;110(26):265503. doi: 10.1103/PhysRevLett.110.265503. Epub 2013 Jun 26.
The interstitial loop is a unique signature of radiation damage in structural materials for nuclear and other advanced energy systems. Unlike other bcc metals, two types of interstitial loops, 1/2<111> and <100>, are formed in bcc iron and its alloys. However, the mechanism by which <100> interstitial dislocation loops are formed has remained undetermined since they were first observed more than fifty years ago. We describe our atomistic simulations that have provided the first direct observation of <100> loop formation. The process was initially observed using our self-evolving atomistic kinetic Monte Carlo method, and subsequently confirmed using molecular dynamics simulations. Formation of <100> loops involves a distinctly atomistic interaction between two 1/2<111> loops, and does not follow the conventional assumption of dislocation theory, which is Burgers vector conservation between the reactants and the product. The process observed is different from all previously proposed mechanisms. Thus, our observations might provide a direct link between experiments and simulations and new insights into defect formation that may provide a basis to increase the radiation resistance of these strategic materials.
间隙环是核和其他先进能源系统结构材料中辐射损伤的独特特征。与其他体心立方金属不同，在体心立方铁及其合金中形成了两种类型的间隙环，1/2<111>和<100>。然而，自五十多年前首次观察到<100>间隙位错环以来，其形成机制仍未确定。我们描述了我们的原子模拟，这些模拟首次直接观察到了<100>环的形成。该过程最初是使用我们的自演化原子动力学蒙特卡罗方法观察到的，随后使用分子动力学模拟进行了确认。<100>环的形成涉及两个 1/2<111>环之间明显的原子间相互作用，并且不遵循反应物和产物之间位错理论的传统假设，即 Burgers 矢量守恒。所观察到的过程与所有先前提出的机制都不同。因此，我们的观察结果可能为实验和模拟之间提供直接联系，并为缺陷形成提供新的见解，这可能为提高这些战略材料的抗辐射能力提供基础。
